Cisco UC500 series router config with Nexvortex\'s SIP service. - repost

Hi, I'm looking for someone who is expert in Cisco Configuration. Currently I've Cisco UC520 that is configure with Nexvortex's SIP. Nexvortex is already deployed and ready to use. SIP trunk is working. I want to add ASA 5510 to the environment and configure Cisco 9971 phones to terminate into the ASA 5510 and connect to the UC520. Currently the Cisco UC520 is connected to the internet through it's firewall and wan interface. You need to register a Cisco CP9971 phone that is already connected with the UC520, but make it work from the internet